Screw anchor



Aug. 10, 1943. A. w. GELPCKE SCREW meson Filed Aug. 15, 1942 INVENTOR Afffiea W' o BY a), 2a.?

ATTORNEY Patented Aug. 10, 1943 a l I 3 53,

- LSCBEW ANCHOR Alfred. 1W- G'lpcke, Brooklyn, N, Y., .ass'ignor .to' The Rawlplug'Company; Inc.,' New York, N; Y.

ApplicationARguSt :15, 1942,Serial No.1:455,ik91 ,i 5

jsclaims; (o1. 85'2.4)'

Thisinventionrelates-to a special type of anchcr for iholding screws or fasteners inmasonry of various kinds. The typeof screwanchor to be herein described is what may be termed in general as of the fibre plug type. Whilenumerous forms of such fibrescrew-anchors have been designed, I have i found, by working with various types ofsuch anchors over quite'a; period of years, that there is still room for'improvement in such style of anchors, and the-presentspecification is directed to describing a new screw anchor which has many advantages 'over prior-art constructions. I

lieretofore fibre screw anchors'ha ve been made up ina sleeve type in'which the sleeve h'asbeen composed of a bundle of longitudinallyarranged fibre strips or cords heldtogether with a suitable binder such as glue or the equivalent.- .Other sleeves or screw anchors have been made-by braiding fibrous strands andtreatingthem with a suitable binder. Still later this braided sleeve was used in combination with aninner 'sleeveof soft expansible metal such as lead, this lastlconstruction being set iorth in Feidmar Patent 1,570,- 234, issued January 19, 1926. 7

I have found from experience that in tlie manufacture and useof a plug of the Feldmar type, in which the inner sleeve is continuous throughout, is impcssibleto get the best holding or gripping'eilect with a given amo mt of material as compared with my improved type of screw anchor to be hereinafter described.

It is therefore the principal object of my invention to providea screw anchor-having manyimproved characteristics, all of which -wiil be hereinafter set forth; 1

To attain the general object of my invention, I take a suitable piece of expansible material, preferably of relatively soft metal such as tin, zinc or lead foil oran alloy of theseor' other metals, of a suitable width and thickness to conform to the size of the screwanchor to be made, and draw this over a mandrel preferably circular of the exterioraof the anchor' would lessen"itsgripping hold on themasonrys Such a thing often happens in -present expansion fasteners when the user-isforced to rub' some lubricant such as soap repeatedly onto the fastener or screw in i order "to permit comple'te insertion of the screw or fastener into the :ianchorzx The-lubricant may be one of several forms, but have secured excellent resultsby-using graphite mixed with petrolatum or paraiiin; i while'the stripmay be treated with-ailubricant-iat the time-of forming or manufactureof the :plugs, lubricant may be applied to the strip during themanufacture ofthe strip materialiper sejor the-lubricantmay be' em- I bodied directly inithe material of :the-stripitseli,

the imain'. thingbeing hhwever, to have a surface which eliminates friction ibetween the, screw and the inner lining, and-produces :aslip between-the inner liningiand-the outer sleeve." v

Immediately: after'fthis 5 lubricated :f strip is formed over the mandrel a {fibrous braid-oi suitable'rnaterial', preferably being resilient suchaas jute; is braided overit. Preferably-the braidfis material to 1 be *usedfibnitheasame :diameter of an:- chor. While the braiding .i's=-:being :applied :over

the inner sleeve c iming, it 'iisr-1sirnultaneously' treated with a suitablebinder such as -gluecor the equivalent: ..A plug-made with a tight braid has the advantage of: I beinggmuch stronger in handling :and can be driven-into a tight hole without buckling'or bending, which feature is I 'may use outside the tightlyflbraided :sleeve in form so that the edges of the ,foilare' in 'lapping relation; that is, the. edges lap in some manner preferably as illustrated in FigureZ for the pur'poseto be hereinafter described. i

This strip is atleast lubricated on what is'to 7 become the inner surface with a suitable lubricant that is rust-inhibitive so as to prevent the corrosion of the screws after they are screwed into place in the anchor, and also to permit the easy insertion and reinsertion of the screw. If the strip is lubricated on both sides there-is an advantage in prelubricating the strip beforeit quantity of lubricant thus getting on the outside 7 which surrounds :thei-nner lining, "a pluralityof parallel strands and theniarsecondbraided sleeve over thesestrandsin order to-obtain theidiame- V ter plug, required; Byusing 'aninner lining, or sleeve having a split longitudinally of its length and lubricated on both. sides, the lapping-edges oi the lining will slip alongon. each other and the inner sleeve will slide under the outer ifibrous sleeve as the serew enpands::thislini-ngor sleeve,

it being understoodqthat the "overlani-s suflicient forlanygivenesize plug so that: the screw that is used with the .plug'will notpexpand the inner sleeve to a point Where theoverlap ceaseszto-rexist or the opening betweenthe edges of thezlining is not so great as-to I permitthe screw t0 come into contact with the fibrous :strands r thefouter sleeve l With this construction maximum expansion of both sleeves takes place; the" screw cutting: .at r 7 least a partial thread on' the-sinner 'lining or sleeve, expanding this sleeve,:'i;og;etherswithxthe o t r's eev o into-tight engagement withla drilled By using a lubricated inner sleeve as described,

the ease of inserting the screw is greatly increased and thescrew may be more easily removed and" reinserted in the hole for making any changes on the fixture fastened by the screw.

In the annexed drawing:

Figure 1 illustrates a longitudinal sectional" pingedges are sufficient so'that for any given size plug the expansion, when a screw is inserted 1.

into the anchor, still leavesrsome lapping so that the screw will not come in contact with the fibrous strands of the outersleeve. In Figure 2 the inner surface of the lining is illustrated as having a-lubricating coating 4 thereover. This is exaggerated in the drawing inorder to illustrate it.

In Figure 3 the outer sleeve ismade up of parallel strands of fibrous material and both surfaces of the inner sleeve are illustrated as having a lubricating coating 4 and 5.

In Figure 4 the outer sleeve is made up of a plurality of layers, the inner layer I being braided, on which is applied a layer of parallel strands 6 as illustrated in Figure 3, and over these parallel strands is applieda layer 1 of braided fibrous material. The construction shown in Figure 4 would be used preferably on the larger sizes of screw anchors, and onthese larger sizes it is preferable to form one end 'of the anchor with a bevel 3 as illustrated in Figure l, or both ends may be beveled. 1

While in Figure 2 I have shown the inner lining as having a lubricating coating on its inner surface, it will be understood that I prefer to also use a lubricatingcoating on the outer surface ofjthe lining, thesame as illustrated'i'n Figure 3.

'While'the foregoing specification refers generally to' the use of the anchor'des'cribed herein in connection with screws, some other types of fasteners may be used in certain cases, such as nails or other pointed devices, as the liner will permit easy driving of the fastener and the tight braiding will give a good holding power when expanded. Furthermore, while I prefer the overlapping construction of Figure 2, there will be cases where the edges of the inner liner may be brought into abutting relation, especially where the'braiding is put on tightly and the holes in the masonry are'proper so that substantially the full effect of the lubricated liner can be obtained betweenthe outer fibrous covering and the fas tener, whether it be a screw, nail or other kind of device.

I have found, after many tests, that such an anchor as herein described is far superior" to anything heretofore produced; that is to say, it

is stiffer and'can be driven into a tight-fitting tively soft metal, the lining being split longitudinally of its length with the split edges normally lying in lapping relationship, at least the inner surface of the lining being treated with a lubricant.

2. A screw anchor comprising an outer sleeve of fibrous material and an inner lining over 'which the outer sleeve is tightly positioned, the

lining being split longitudinally with the split edges slidable one on the other without bringing the outer sleeve into direct contact with a screw which may be inserted into the anchor, at least the inner surface of the lining being treated with a lubricant.

3.A screw anchor comprising an outer sleeve of fibrous material and an inner lining of relatively soft metal, the lining bein split longitudinally with .the split edges positioned to slide one on the other without bringing the outer sleeve into direct engagement witha screw which may be inserted intothe anchor, the lining having of fibrous material and an inner lining of relatively soft metal over which the outer sleeve is tightly braided, the lining being split, longitudinally with the split edges overlapping sufficiently so the insertion of a screw within the lining will not spread the lining enough to allow the screw to engage the outer sleeve, the lining having its surfaces treated with arust-inhibiting lubricant.

5. A screw anchor comprising an outer sleeve composed of a plurality of layers of fibrous material and an inner lining of expansible material which will allow a thread to be out therein when a screw is forced into the lining, the lining being split longitudinally with the split-edges slidable one on the other, the lining having its surfaces treated with a suitable lubricant.

6. A screw anchor comprising an outer sleeve of fibrous material and aninnerlining of expansible material, the lining being split longitudinally with the split edges slidable one on the other without exposing the outer sleeve to thfidlr rect action of a screw, the lining having at least its inner surface treated with a rust-inhibiting lubricant.

7. A screw anchor composed of an inner and an outer sleeve, the outer sleeve being of resilient fibrous material, the inner sleeve being split longitudinally and also being substantially circular in cross-section with edges normally overlapping preferably to an extent such that whenthescrew is all the way into the anchor the threads of the screw will not come in contact with the outer V sleeve, at least the inner surface of the inner sleeve being treated with a suitable lubricant.

8. An anchor for a fastener comprising an outer sleeve of fibrous material and an inner lining of relatively soft expansible material, the lining being split longitudinally of its length with the split edges normally lying inlapping relationship and slidable one on the other, at least the inner surface of the lining being treated with a lubricant.

9. An anchor for a fastener comprising an outer sleeve ofrfibrous material and an inner lining of relatively soft expansible material, the lining being split longitudinally of its lengthwith the two split edges normally lyingin close juxtaposition, the lining having its surfaces treated with a suit able lubricant. 

